L4 Reading Difficulties Flashcards
What is dyslexia?
Learning difficulty affecting skills involved in accurate and fluent word reading and spelling
- slow word processing
- spelling
- visual perception
- working memory
- attention
- planning
Who has dyslexia?
9-12% of the population
More frequent in males than females
What is the multi-deficit model by Pennington 2006 ?
Can be used for multiple behavioural disorders but made specifically for dyslexia
Look at behaviour when trying to diagnose
Behavioural disorders,
Cognitive processes,
Neural systems,
Aetiological risk and protective factors
What evidence is there to suggest that there is a genetic basis?
Reading ability seems to be heritable
Heritability estimates 40-60% - varies
Child is at greater risk if parents have dyslexia (Schulte-Korne 1996)
From twin studies Stevenson 2987 found heritability estimates of 29% for reading abilities and 73% for spelling abilities
What are candidate genes?
Many genes that may be used when spelling and writing
- KIAA0319
- DCDC2
- ROBO1
What is the evidence for candidate genes?
KIAA0319 - affects neural migration and radial glia adhesions, evidence from genetic pooling of 223 subjects with DD
DCDC2 - particularly associated with the severe phenotype of dyslexia, longitudinal study found that genetic risk from DCDC2 strengthens the link between pre-reading maze learning
What is the difference of pleiotropy and polygenicity?
Pleiotropy - one gene effects many things
Polygenicity - many genes contribute to single trait
What is the generalist genes hypothesis?
Genes for LD are same as those for normal variance
Genes for symptom A are same as those for symptom B
Genes for one LD are same as those for another LD
How do genes influence dyslexia?
Genetic correlates with other types of neurodiversity and psychiatric disorders
- associations between dyslexia risk and ADHD risk + bipolar, schizophrenia
Genes interact with the environment
- interacts change overtime
- higher influence when socio-economic status is high
What are some environmental factors?
Home learning environment
School conditions
Socio-economic status
Stress
What did Dilnot et al 2017 research?
Investigates risk factors for predicting attention, behaviour and reading readiness in those at risk of dyslexia
Home literacy environment
No main effect or family risk once environment controlled
Environment had a large effect for expression of dyslexia
What is the phonological deficit theory?
Deficit in phonological awareness - recognising spoken parts of words
What did Swan and Goswami 1997 find about the phonological deficit theory?
Measured picture naming, and phonological abilities
Found children with dyslexia had poorer performance for picture naming than neurotypical controls
Linguistic skills - children with dyslexia performed similarly to reading age controls, poorer performance for phenomics tasks
Both groups had better performance for high frequency words
What is the atomisation hypothesis?
Dyslexia is the result of a deficit in automatic processing
Difficulty atomising reading behaviours once learnt
Might be caused by reduced activation in the cerebellum
What was Moores 2003 research into the atomisation hypothesis?
People with dyslexia and controls took part in tasks that required focusing and shifting attention between two targets
Found both groups similar results for focusing
But dyslexia group performed worse than controls when the task relied on shifting attention
Recognition di not generalise when criteria were changed
